Radiation sensitive hit detection arrangement

ABSTRACT

A hit detecting and indicating arrangement for a target having a light source thereon, in which the hit detection and indicating arrangement includes a light sensitive detection element with a digital gray scale filter for attenuating the light energy from the target light source as a generally inverse square function of the distance of the photoscope from the light source. The photoscope includes a lens system and a field mask, the field mask having a generally triangular field aperture which defines the maximum area of light transmission through the digital filter.

wuwu oldtta rawm 1 1 [1 1 3,780,300 Kott Dec. 18, 1973 [54] RADIATIONSENSITIVE HIT DETECTION 3.001.437 9/1961 Taylor 250/203 x ARRANGEMENT3,035,479 5/1962 Baltosser et a1. .1 250. 226 X 3,041,011 6/1962 Dhanes250/203 X 1 Inventor: Michael Marlboro, Mass- 3,060,360 10/1962Tomek..... 250/220 x 3] Assignee: AA! Corporation, cockeysvme Md.3.260.152 7/1966 Aston 350/314 X [22] Filed: 1972 PrimaryExaminer-Walter Stolwein [2]] App] 217 04 ArwmeyRegina1d F. Pippin, Jr.

Related U.S. Application Data [63] Continuation of Ser. No. 888,266.Dec. 29, I969 1 1 ABSTRACT abandoned.

A hit detecting and indicating arrangement for a target having a lightsource thereon, in which the hit de- 250/237 g p gg tection andindicating arrangement includes a light [58] i 226 sensitive detectionelement with a digital gray scale 250/237 R, 237 G; 350/162 SF 205 214filter for attenuating thenlig ht energy fromf the target 235 317 3]356/4 1g t source as a genera y inverse square unction o the distance ofthe photoscope from the light source.

The photoscope includes a lens system and a field [56] References cuedmask, the field mask having a generally triangular field UNITED STATESPATENTS aperture which defines the maximum area of light 3,551,68012/1970 Knight 250/203 X transmission through the digital filter.3.419.726 12/1968 Olsen 250/239 X 2,244.507 6/1941 Thomas 350/314 X 38Claims, 6 Drawing Figures APPROXIMATE EFFECTIVE SHWT RANGE FIELD OF VIEWAT OBJECTIVE LEN ,-LONG RANGE FIELD OF VIEW I m0 msx -1- I FIELO msxuAsK L LIGHT azncou h 31 41 5t FIELD LENS L'' E EIODE r TARGET TRESPONSE FIELD AT FIELD MASKAPPROXIMATE I FIELD MASK EFFECTIVE RESPONSEFIELD AT MAX EFFECTIVE RANGE FIELD MASK AT MIN EFFECTIVE 2! FILTER LINEOF DESIRED 1 TARGET MAX TRANSMISS ON 4 6| AREA RATIO T l g v Q t' 2 Rmalmm mln '0 P 11 PHOTOSCOPE I mmcnon AMPLIFIER 13:53.0

OBJECT VE LEKS FILTER MASK FIELD MASK OBJECTIVE LENS 21 FILTER MASK 4|FIELD MASK 3 FIELD LENS 5I I I I I FIG. 3

MICHAEL A KOTT INVENTOR ATTORNEY PAIENIEDuEc 1 8 I975 3.780.300

snm an; 5

FIG.4

MICHAEL A, KOTT INVENTOR BY K ?M %w ATTORNEY TRANSMISSION RATIO (LOGSCALE) PAIENIEB DEC I 8 I916 SHEET 5 BF 5 DESIRED T2 M TRANSMISSION T Xx x=0 =B x=S x=e+5 max SPOT CENTER DISTANCE FROM X ON FILTER MASK(LINEAR SCALE) EXAMPLE OF EFFECTIVE WORKING ZONE AT MASK EXAMPLE OFWORKING ZoNE AT MASK MIN RANGE R EXAMPLE OF ZONE AT MASK FOR MAX 1 RANGER FOR R IsR I MiCHAEL AI KOTT INVENTOR ATTORNEY RADIATION SENSITIVE HITDETECTION ARRANGEMENT This is a continuation, of application Ser. No.888,266 filed Dec. 29, 1969, now abandoned.

This invention relates to a hit detecting and indicating arrangementincluding a photoscope or other analogous signal detecting device havingthe capability of detecting and indicating the occurrence of hits upon amovable target which has a light source detectable by the photoscope,and which may be located at varying distances from the photoscope.

ln hit detection systems for simulating the occurrence of hits scored bythe operator ofa weapon or simulated weapon, it is desirable to be ableto detect the occurrence of hits over as wide a range of target distanceas possible. Various arrangements have been proposed and employed toeffect some degree of capability in this respect, including theemployment of photodiodes which are variable in response across theirlateral surface, the employment of filter masks between the detector andthe light source, and the employment of dual detectors with dual lenssystems. The present invention enables the employment of a singledetector, such as a photodiode, while enabling the detection of hitsover a relatively wide range of distances of the target from thedetecting and indicating device, (although such may be employed in dualdetector-lens systems, if desired, for even greater range), and furtherenables this function to be obtained without the necessity for a largediode or a special diode with special configuration and/or response.

In carrying out this invention a special analog simulating digitalfilter mask is employed in the hit detecting and indicating device,between the target signal detecting element (which may be and ispreferably a photodiode) and the target. This special filter mask maytheoretically be a digital filter mask in entirety, but as a practicalnecessity is a combined analog and digital filter mask. The degree ofcombination of the digital and analog filter portions of the mask isgenerally a practical matter, depending to a substantial degree upon thematerials and techniques employed in forming the mask. The generalfunction of the mask is to enable the detecting and indicating system toaccommodate the normal target signal attenuation which occursproportionately to the square of the distance of the target from thedetecting device, while enabling the detection and indication of hitswithin a varying aiming angle as an inverse function of the targetdistance from the detecting device.

Still other objects, features and attendant advantages will be obviousto those skilled in the art from a reading of the following detaileddescription of a preferred embodiment constructed according to theinvention, taken in conjunction with the accompanying drawings wherein:

H6. 1 is a schematic illustration of a hit detecting and indicatingarrangement and incorporating the novel combination filter according tothe invention.

FIG. 2 is a schematic view of the basic elements of the hit detectingarrangement of FIG. 1, and illustrating schematically the relative sizesof these elements.

FIG. 3 is a schematic illustration of the elements of HO. 2,illustrating the relative axial distance spacing thereof.

FIG. 4 is a fragmentary greatly enlarged face view of the novel filtermask according to the invention, and

illustrating various light spot pattern and position as pects withrespect thereto.

FIG. 5 is a more greatly enlarged schematic illustration of the holearea forming the filter section of the filter mask of the preceedingfigures, the relative size of the small digital holes being exageratedfor clarity of illustration.

FIG. 6 is a generalized diagram illustrating various transmission curveswith respect to the filter mask according to the invention.

Referring now in detail to the figures in the drawing, a photoscopegenerally indicated at 11 is provided for detecting the ability of anoperator to aim the photoscope at a target T, such as a tank vehicle,which is provided with a detectable target signal generating means, suchas a light beacon L. The light beacon L may generate a light beam whichis in the visible or invisible spectrum, as may be desired, and which isdetectable by the photoscope when properly aimed thereat, as will belater described. The light beacon L may be continuously generating itslight beam, or may be triggered to generate such by the operator of thephotoscope, as through the employment of a further signal and responsesystem, which does not itself form a part of the present invention, andwhich may be of a type such as disclosed in U.S. Pat. Nos. 3,104,478 and3,l69,l9l.

It is desired that the photoscope ll be capable of detecting simulatedhits on the target T over a substantial range of distances of the targetT from the photoscope 11. As the light beacon L is normally of constantintensity, it will be apparent that the light reaching the photoscopewill vary generally inversely to the square of the distance of thetarget T from the photoscope, and in addition there are atmosphericattenuations which it may be desirable to accommodate for givensituations. The primary variation of amplitude of the light signalreaching the photoscope 11 from the target T and its light beacon L iscaused by the inverse square variation as a function of range of thetarget, and this invention is primarily directed toward accommodatingthis variation, although it will be appreciated that other variationsmay be generally accommodated, within limits, by the invention.

The photoscope 11 includes an assembly of elements which may be suitablyhoused within a tubular or other housing, which is not shown, as suchitself does not form a part of this invention and may be readily formedby one skilled in the art. The primary elements of the photoscope 11 arean objective lens 21 which collects light from the light beacon L, afield mask 31, a filter mask 41, field lens 51 and photodiode 61. Theobjective lens 21 and the field lens 51 may each suitably beconvex-convex, and the spacing of the elements 21-61 of the photoscope11 is such with respect to the objective and field lenses that the focallength f,, of the objective lens is equal to the center-to-centerdistance between the objective lens and the field mask 31, with thefocal lengthflof the field lens being defined by the following equation:

where S is the center-to-center distance between the objective lens 21and the field lens 51, and S, is the distance between the center planeof the field lens 51 and the detecting face of the photodiode 61.

Thus, the light collected by the objective lens 21 will be focused atthe plane of the thin (cg. 0.001 in.) field mask 31, and this circularpattern of light will converge to its smallest substantially point sizeat the field mask 31. The light beam diverges and is enlarged as itpasses rearwardly away from the field mask 31, and has a discretegenerally circular spot size S at the plane of the filter mask 41. Forpurposes of discussion hereinafter, this light beam spot at the plane ofthe filter mask 41 will be designated as LS, and, as noted, such spot LSwill have a finite size S, which is a function of the focal lengthspacing f between objective lens 21 and field mask 31, the diameter oflens 21, and the spacing between field mask 31 and filter mask 41. For agiven objective lens focal lengthf and corresponding interspacingbetween the objective lens 21 and field mask 31, the filter mask 41 maybe spaced rearwardly of the field mask 31 to achieve a desired size Sfor the light spot LS from the target light beacon L.

Connected to the output of the photodiode 61 is a threshold trigger 71which may suitably be a Schmitt trigger circuit, which in turn isconnected to an amplifier 81 and indicator 91. The threshold triggercircuit 71 may suitably be selectively set to enable the indication ofthe presence of hits detected by the photoscope 11 as indicated by thepresence at the diode 61 of at least a given selected minimum quantum oflight energy on the effective surface of the diode 61 after passingthrough the photoscope 11. This setting may readily be made on anempirical trial basis, if desired.

in the photoscope 11, the field lens 51 accepts all light energyreaching such and which has passed through the assembly of the objectivelens 21, field mask 31 and filter mask 41, and images this collected,masked and filtered light from the objective lens onto the face of thediode 61. In this manner the diode 61 may be made relatively small ascompared to what would otherwise be required without the employment ofthe field lens 51.

The light collected by the objective lens 21 is masked and filtered bythe field mask 31 and filter mask 41 respectively, prior to passingthrough the field lens 51 and being imaged onto the diode 61. The fieldmask 31 has a triangular aperture 33 formed therein, and generallyaligned with this triangular aperture 33 is a digitalanalog filtersection 43, 45 on the filter mask 41. The triangular aperture 33, takenin conjunction with the focal length of the objective lens 21 and thespacing of the filter mask 41 from the field mask 31, defines themaximum overall field of view as such appears at the filter mask 41. Asis generally schematically illustrated in FIG. 1, the physicaldimensional triangular field of view through the field mask 31 isdirectly proportional to the range ofa target from the photoscope 11. Itwill be appreciated that inasmuch as the target T is of constant size,such increasing physical dimensional field of view effected by the fieldmask 31 would itself alone result in a variable error in hit indicationat all ranges other than some given single range, the degree of errorbeing a function of the actual range relative to this given range. Thedesired effectively detected field of view through the field mask shouldbe substantially constant for all ranges, over the working scope oftarget ranges, and the general configuration of the triangular aperture33 should generally conform to the acceptable hit pattern over the giventarget T, this triangle being effectively inverted in form as indicatedin FIG. 1 at the zone of the target, to thereby define the maximum zonewithin which the light beacon L may be located while still enabling theregistry of a hit by the diode 61. threshold trigger 71, amplifier 81and indicator 91.

The field of view at the field mask is modified to form the effectivelydetected, or effective, field of view therethrough, by the incorporationof filter 41, by which the quantum of light energy within the light spotLS is attenuated generally as a function of the displace ment of thelight spot LS downwardly from the apex of the triangular aperture 33.For inverse square light attenuation compensation, this variation inattenuation is desirably directly proportional to the square of thexaxis displacement of the center of the spot LS from its base or originpoint which latter point is the point of focus of the light beam at theprecise upper apex of the triangular aperture 33 in field mask 31. Thiswill yield a transmission ratio through the filter mask 41 which wouldvary inversely as the square of the displacement of the center of thespot LS from its zero position. This theoretical zero position may, ifdesired, correspond to the actual position of the light spot LS when thephotoscope is precisely axially aligned with the target light beacon Lor the theoretical zero position may be offset upwardly if desired ornecessary in a given instance. It will be appreciated that by employingsuch a variable transmission ratio through the filter mask 41, thisenables accommodation of the variation in light received by theobjective lens 21 as an inverse square function of the range of thetarget T from the lens 21, as the approximate effective triangularaperture portion of the field mask aperture 33 may thus beproportionately de creased inversely proportional to increase in rangeof the target T, and directly proportional to angular change in angularfield of view of the target T, as generally indicated at positions R andR in the schematic illustration of FIG. 1.

The effective working zone at the field mask or the filter mask may bedefined as the zone over which the target light source L may be imagedat the field mask, or the filter mask respectively, and yieldtransmitted light spot energy from the target light beacon L through thefilter mask and field lens to the diode, which transmitted energy valueis above that which would enable the diode to trigger the triggercircuit for a given threshold setting for the trigger circuit.

It is theoretically possible to employ a direct analog photo-emulsionmask of varying transmission density for the filter mask 41 in order toachieve this result, although in actual practice such is quite difficultand expensive to carry out on a uniform or reliable basis, and such aphotoemulsion filter also normally has the substantial disadvantage ofchanging with the passage of time, as is characteristic of developedfilm emulsions. Thus, although the photographic filter mask 41 withsmoothly varying density and transmission ratio is theoreticallyfeasible and in this respect theoretically most desirable according tothe broad aspects of the invention, such is in actual practice difficultto achieve. l have found that a practically suitable filter mask 41 canbe formed in a substantially different and practically satisfactorymanner, and which may from a generally practical standpoint sufficientlyapproximate the desired transmission ratio curve T, where in which x isa function of the displacement of the light spot LS from its base ororigin point, and K is a constant multiple. The filter section of mask41 is generally indicated at 43, 44, 45, and is formed by a relativelylarge light passing aperture 43 having an edge 43a which forms anoptical knife edge, and a plurality of sets of relatively much smallerapertures or holes 47 which may be, and are desirably from a practicalstandpoint, of constant diameter and which vary in spacing therebetweenas a function of the distance x of succeeding rows of such holes from azero point or line corresponding to the position of the spot LS at thepoint of tangency of the spot LS with the knife edge 43a. The formationof the holes 47 may be readily achieved in the middle and lower zones ofthe hole section 44, but it will readily be appreciated that if physicalholes are to be physically formed in a sheet of material, which is thepreferred manner of formation and construction, there is normally apractical limit beneath which it becomes extremely difficult, if notpractically impossible, to consistantly form substantially uniform holes47 in the sheet forming the filter 41. From a practical standpoint inrelatively thin sheets (e.g. 0.001 inch) this has been determined to beapproximately that spacing where the minimum center-to-center distance Gbetween holes is equal to 21-], where H is the diameter of the holes inthe section 44, and G, is the center-to-center spacing between adjacentholes generally. Thus, in the zone of the projected apex of field masktriangular aperture 33, the employment of holes 47 in the filter mask 41reaches a practical impossibility when such are physically formed in thedesired structural hole method and construction. ln the case where aphotographic emulsion density method is employed for formation of theselight passing(or blocking or attenuating, in such case) apertures 47 ona substate such as plastic, glass or the like, with the remainingsurrounding zone being unifonnly opaque or of other substantiallydifferent optical transmissivity, it will be appreciated that, dependentupon grain size of the developed emulsion, the mask 41 may be formedwith such photographic apertures 47 disposed even closer together, andaccordingly with a very fine grain emulsion one might conceivably havesuch apertures 47 extend substantially to the upper apex position of thespot LS as it passes through the apex of triangular aperture 33 and ontothe filter mask 41. Such is within the contemplated extent of myinvention, but as before mentioned, such is normally not preferred,particularly in view of the practical difficulties encountered inphotographic emulsions changing their density and transmissioncharacteristics over a period of time.

A suitable practical solution to this difficulty has been achieved byemploying a knife edge signal attenuation transition zone in the zoneabove the upper row of holes 47 which are at the minimum interholespacing 2H. It has been found that the combination of transmission ratiocurves as the spot LS is displaced axially from its zero point indicatedin FIG. 5 at x, where the spot is tangential to the knife edge 43a oflarge aperture 43, downwardly along the x axis and onto and along thedigital hole section 44, may be made to generally approximate forpractical purposes the desired transmission ratio curve T, for a givenrange of target distances .511: was 7 As the light from target beacon Lpasses through its focal point in plane of triangular apertured fieldmask 31, and subsequently converges to form a spot LS in the plane ofdigital mask 41, it will be appreciated that the total effective lighttransmission area of the filter mask 41 will be determined by the sizeof triangular apentire 33, the spacing of this mask 31 and mask 41, thediameter of lens 21, and the focal length f and for a given size S ofspot LS, the effective area of filtering of signals from the target Tmay be indicated by the broken line 44 which extends beyond the directlysuperimposed outline of the triangular aperture 33, by an amount equalto 5/2. Thus, the zone over which the holes 47 are formed is desirablylarger than the effective filter area outline pattern 45 by a smallamount sufficient to provide desired hole spacing within the effectivefilter pattern area 45.

Taking the transmission ratio curve T, which results from displacementof the light spot LS from point zero, designated in FIG. 5 as x,,,vertically downwardly along the space in the zone from x 0 to x S, atwhich lateral position the light spot LS is completely beneath the knifeedge 43a, and ignoring the light transmission through the digital holesection 44, the transmission ratio T, for this zone of spot travel maybe defined as T, l/1r (1r arc cos 5- 2x/S+ r sin 2 are cos S- and thisequation being applied for values of x from x O to x S, only.

Considering next the average transmission ratios T and T; as the lightspot LS is traversed along the x axis overfiie digital hole filtersection 44, the following assumptions and practices have been found tobe practical in order to provide a combined curve T, T, T, whichgenerally approximates the desired transmission curve T,, which lattercurve T, is generally illustrated in FIG. 6 in broken line and is soindicated.

These assumptions include:

G,. center-to-center hole spacing along the Y axis for any given row ofholes at a distance x, from point or line x,,, line x, being the X axislocation at the center of spot LS when the lower edge of the spot istangential to the knife edge 43a of aperture 43.

C3,. G, minimum center-to-center hole spacing 'of row of holes 47nearest knife edge, at distance x, from line 0.

fififg gmxjilfifli lll 9f h fl i l fi from the knife edge 43a, andrepresents the greatest interhole spacing for a given digital holefilter zone 44, independent of other cutoff values which may be effectedby the field cutoff boundary of field aperture 33.

H hole diameter for all holes 47.

G,,,,,, 2H as a practical lower limit.

S diameter of light spot LS For "practical purposes the filter mask 41is formed of thin metal (e.g. 0.001 inch thickness) which is opaque,thus rendering the transmission ratio of filter mask 41 equal to zero atall zones other than hole zones formed by holes 43 and 47, and withinsuch holes the transmission through any given hole area is assumed to beunity, It will be appreciated that both of these extremes may bemodified respectively by using different transmission density materialfor the sheet forming mask 41, and lesser than percent transmissionthrough the island zones of hole 43 and/or 47, as with a purelydeveloped emulsion film mask 41. For purposes of approximating theaverage transmission value T, a generalized equation may be derived,based on the assumption that interhole spacing G in both the X and Ydirections approximates a square of substantially uniform size over thecircumferential zone of the spot LS.

It will be seen that for a matrix of holes with such a uniformly equalsquare inter-hole spacing of the holes the value T being the averagetransmission ratio through the gridwork of holes in an opaque sheet, thesize of the error ofT being inversely proportional to the value of (S H)and directly proportional to G.

This theoretical gridwork is not found in the desired digital filterzone 44 having holes 47 therein, as the interhole spacing is varied as afunction of the distance of a given lin of holes from line x, in orderto approximate the desired inverse square light transmissioncompensation. However, for relatively large values of S with respect toH and G, with relatively small changes ofG with respect to itself fromline to line, it will be appreciated that this approximation equation Tmay be applied advantageously to the gridwork of holes according to thepresent invention, it being recognized that the greater the value of Gthe larger will be the possible error in the value T, for any givenvalue of S as the diameter of the spot LS. Based on this assumption, fora given transmission TI in the zone of the row of holes at x, distancefrom line or point x,, an approximation value for T, may be derived asCorrespondingly,

where G, is the center-to-center hole spacing along the Y axis at therow of holes x, distance from 1: Thus, given the desired transmissionratio T, for a given line position x, on the mask 41, and assuming 1} 7,at the light zone involved, it will be seen that the interhole spacingG, may be derived for the particular line position x,,.

The inter-row spacing of adjacent rows of holes along the X axis may bedetermined in various ways, as desired, the simplest method being toobtain first the Y axis value (i.e., G, of G, for the row of holesclosest to the knife edge 43a, which value may be generally determinedfor any given hole size, from the foregoing practical assumptio risfForthis Y purpose, the value T is selected to that value which willcomplement another curve T to be subsequently described in more detailhereinafter, for the given selected distance x the value x,, of whichwill likewise be selected on a trial and error basis with this view inmind.

After arriving at the value O one acceptable and simple methodofarriving at the x distance spacing of the next succeeding line ofholes, where G, for any two successive rows represents this inter-rowspacing for any two successive rows where the rows are at x,. and xdistance from X0. is to msmg g equal to the value of G Thus, oncethe grlocation of the first line of holes is established, all succeeding linesmay be readily located.

Alternatively, the inter-row spacing G, may be increased as a functionof the interhole spacing G and 656 for the respective two adjacent rows"of holes. In this respect, this interrow spacing may be madeapproximately equal to the average of the values 0, and G for therespective two adjacent rows of holes, and which may be written as ifthis latter relationship is assumed, rather than the simpler formerrelationship of it will be appreciated that repeated trial and errorcalculations may be employed to determine the desired values of G y forsucceeding rows, as this interrow value will be dependent upon bothvalues G, and G for succeeding rows of holes, by definition, and thesevalues are in turn dependent on the x distance location of therespective rows of holes 47 from 1,. This particular manner ofincremental variation of G, best lends itself to solution by computerprogramming, particularly in view of the requisite trial and errormethod of solution, although it will be apparent that such may bederived by repeated hand calculations on a trial and error basis inorder to get a desired degree of approximation of the desired curve r.

These assumptions further include the assumption that in the zonebetween the first row of holes 47 lying closest to the knife edge 43a,and extending over an x distance of S, the holes may be assumed to begenerally equally spaced from a generally practical approximationstandpoint, although in fact the holes are disposed with increasingspacing over this zone, and the resulting curve T, in this area in factassumes a lesser transmission ratio amplitude and curve slope as xapproaches the value of B H, than is otherwise shown by the assumedapproximation. However, from a pratical standpoint this is not a seriousdeficiency, as the entire curve is itself only an approximation, andthis degree of error may as a practical matter be acceptable in variousinstances. This assumption for t he purpose of deriving the transmissionratio curve T, as the spot LS first moves onto and subsequently fullyonto the hole area applies for the values of x from x B to x B S, whereB is the distance between the knife edge 43a and an imaginary linetangential to the facing side of the first row of holes 47 at position xConsidering the closely spaced hole zone between x B and x B S as afilter having a generally constant density with an effective lighttransmission ratio T of less than I.

and having a general knife edge formed by the first row of holes at linex,, T may be generally approximated as where T represents theapproximate equation for translation for the spot LS over a knife edgetransition zone from zero transmission into an adjoining zone of fulltransmission, and where represents the equation for the approximatetransmission ratio of this initial hole filter zone, based on theassumption that the entire zone has a transmission ratio correspondingto some given interhole spacing, which for purposes of simplicity andpracticality of computation is assumed to be equal to the interholespacing of the first line of holes at x cl osest adjacent to the knifeedge 43a. The equation for T KEH may be approximated generally as andfor the assumed value of G 2H 7T THKEH =fi' This value 11/16 representsthe transmission ratio modifier which is necessary in order to convertthe knife edge equation T to the actual approximate curve for thesituation where the transmission ratio beneath the knife edge is notunity, but is in fact T which is under the present assumptionsapproximately equal to 11/ 16.

The generalized equation for the transmission ratio T along theremaining portion of the digital hole filter area 44 may be written asTggmv and is to be applied for values of x from x B S to x =x. ,,,+S,assuming that the light spot LS maybe translated over this total area,which of course may be modified as a total by effective lateral fieldlimitsimposed by the boundary of triangular field aperture 33.

Thus, the equation T, and T, combine to form the generalized approximateequation for the transmission ratio of the digital hole filter zone 44,and the combined transmission ratio curve for these generalizedequations is indicated at T, and T; on the graph of FIG. 6, in which T,represents the curve between values 1 B and x B S and T, represents thecurve portion which extends between the values ofx B S to x z x S.

Referring further to FIG. 6, it will be seen that the curve; T drops ofiabrup tlyin the zone wherex .t'x where .Iy is the field cutoff boundaryline effected by the lower edge of the triangular field aperture 33. lnaddition, it will be noted that in the zone between x 0 and x B S, thecombined average transmission ratio curve T, T, T differs in varyingamounts from the desired transmission ratio T,. This variation may betolerated for practical purposes, although it will be apparent that ifso desired the hole spacing and/or the value of B may be modified tobring the curve in this portion into closer relationship to the desiredtransmission ratio curve T this latter being capable of accomplishmentby further trial and error computation, or by analogous computerprogramming if so desired. The curve T may be made to closelyapproximate the desired transmission ratio T in the zone from x B S tox=srinasmuch as the interhole spacing may be adjusted from row to row asnoted in the discussion above, although it wil be readily appreciatedthat this average value is in fact only average and that for any givenposition of the spot LS within this zone a degree of error may bepresent, as the filter system in this zone is in fact a positionallyvarying digital approximation of the desired analog curve.

As an illustration of a practical example which has been derived byrepeated trial and error calculations according to the invention, ametal mask 41 has been derived and employed with a sheet thickness of0.001 inch, and on which the diameter S of the light spot LS is 0.050inch, the spacing B =0.0l15 inch, the hole size H of holes 47 0.001inch, and as a practical method of reliably forming and locating theupper apex edge zone of the triangular field cutoff aperture 33 such hasbeen formed with a minute flat across the apex (e.g. 0.002 0.005 inch)and this flat apex field stop at the apex of triangular field aperture33 is disposed slightly below (e.g. 0.003 0.004 inch) line x, (asdiscussed in connection with FIG. 5), thereby effectively shifting thebeginning operational zone for values ofx in the ap proximation curve TT T as noted schematically in FIG. 6, this being also somewhat desirablein view of the relative poor quality approximation of the curve T, inthe zone adjacent x, with respect to theoretical zero position line x,,.In the specific illustrative value example this initial displacement andeffective beginning operational zone has been located at x 0.003 inch.

While the invention has been described with respect to a preferredphysical embodiment constructed in accordance therewith, it will beapparent that various modifications and improvements may be made withoutdeparting from the scope and spirit of the invention. Accordingly, theinvention is not to be limited by the particular illustrativeembodiment, but only by the scope of the appended Claims.

That which is claimed is:

1. For use in a hit indicating arrangement having a movable targetsource of electromagnetic wave signal emanations, a selectivelyangularly aimable hit detector for detecting the aiming of said detectorat said source within a selected zone indicating a seorable aimed hit,said hit detector being selectively angularly movable and comprising:

electromagnetic wave signal detection means,

and a mask for said signal detection means,

said mask forming a knife edge signal attenuating zone adjoining asignal passing zone,

said mask having a further signal attenuating zone interspersed withspaced signal-passing apertures,

and selectively angularly movable means for forming said signalemanations into a beam of discrete cross-sectional size substantiallysmaller at said mask than either of said signal attenuating zones,

the lateral position of which beam at said mask is a function of thedirectional aiming of said hit indicator in the direction of andrelative to said target.

2. A bit indicator according to claim 1, further comprising thresholdgate means responsive to the output from said detection means,

and indicating means operatively connected to the output of saidthreshold gate means,

said threshold gate means enabling indication operation of saidindicating means upon the output of said detection means exceeding aselected quantum value.

3. A hit detector according to claim 1,

said signal attenuating zones comprising signal blocking zones.

4. A hit detector according to claim 1,

said spaced signal-passing apertures being disposed in rows ofincreasing inter-aperture spacing as a function the transverse distanceof a row from said knife edge.

5. A hit detector according to claim 1,

the inter-row spacing increasing as a function of the transversedistance of a row from said knife edge.

6. A hit detector according to claim 4,

said apertures forming an envelope tapering outwardly in a transversedirection away from and normal to said knife edge.

7. A hit detector according to claim 5,

said knife edge being disposed in signal blocking relation at the medialsection of said detector.

8. A hit detector according to claim 6,

said detector being of generally uniform response across its effectivesignal detector width as determined by the signal passing portions ofsaid mask.

9. A hit detecting arrangement for a target having signal emanationstherefrom comprising:

a detector responsive to said signal emanations,

mask means for said detector,

said mask means including a first signal passing section affording afirst signal response curve, and a second different signal passingsection affording a second modifying signal response curve,

one of said signal passing sections being formed by multiple discreteattenuation zones each of which has substantially the same unit value oftotal signal attenuation therepast, and which discrete signalattenuation zones are varied in spacing therebetween to effect acorresponding varied signal response curve by a signal beam traversedacross said one signal passing section,

the signal output curve of said detector being a composite of saidsignal response curves,

and means selectively angularly movable relative to said target, forforming signal emanations from said target into a beam of discrete crosssection substantially smaller at said mask means than either of saidfirst or second signal passing sections,

and the said beam being movable across said mask means.

10. A hit detecting arrangement for a target having signal emanationstherefrom comprising:

a detector responsive to said signal emanations,

mask means for said detector, said mask means including a first signalpassing section affording a first signal response curve, and a seconddifferent signal passing section affording a second modifying signalresponse curve, the signal output curve of said detector being acomposite of said signal response curves, and means selectivelyangularly movable relative to said target, for forming signal emanationsfrom said target into a beam of discrete cross section substantiallysmaller at said mask means than either of said first or second signalpassing sections, and the said beam being movable across said maskmeans, said first signal passing section having an effective knife edgesignal transmission attenuation transition zone with a first signaltransmission zone on one lateral side of said signal transmissionattenuation transition zone, and having a signal attenuation zone ofgreater signal attenuation effect than said signal transmission zone anddisposed on the opposite side of said signal transmission attenuationtransition zone, and said second signal passing section comprising aplurality of spaced discrete signal passing zones of varying spacingacross said second signal passing section as a general function of thespatial relationship of said spaced discrete zones to said knife edgetransition zone, and affording a second signal response curve differingand generally complementing said first signal response curve togenerally simulate a desired total signal response curve. 11. A hitdetector arrangement according to claim 10,

said second signal passing section including a signal attenuationpattern portion having a first signal transmission zone which has asignal attenuating characteristic, and an effectively generally knifeedged signal attenuating portion of increased signal attenuation effectadjoining said first signal transmission zone and having a signalattenuating characteristic of greater signal attenuation effect thansaid first signal transmission zone. 12. A hit detector arrangementaccording to claim 11,

both of said knife edged attenuation portions being commonly adjoiningand having oppositely facing effectively knife edged signal transmissiontransition zones spaced from one another. 13. A hit detectingarrangement for a target having signal emanations therefrom comprising:

a detector responsive to said signal emanations, mask means for saiddetector, said mask means including a first signal passing sectionaffording a first signal response curve, and a second different signalpassing section affording a second modifying signal response curve, thesignal output curve of said detector being a composite of said signalresponse curves, and means selectively angularly movable relative tosaid target, for forming signal emanations from said target into a beamof discrete cross section substantially smaller at said mask means thaneither of said first or second signal passing sections, and the saidbeam being movable across said mask means,

said second signal passing section comprising substantially the sameconstant size light transmission zones and being of zonally varyinglight quantum transmissivity. 14. A hit detector arrangement accordingto claim 10,

said zonally varying light quantum transmissivity zones being formed byconstant sized holes in said mask at varying spacing. 15. A hit detectorarrangement according to claim 13,

said first signal passing section including an aperture bounded by aknife edge, said knife edge being spaced from said varyingly spacedholes. 16. A hit detector arrangement comprising: electromagnetic wavesignal detection means, and a mask for said signal detection means saidmask having a signal attenuating zone and a plurality of variably spacedapart substantially the same constant size signal passing zones oflesser attenuation than the total attenuation of said signal attenuatingzone and being within said signal attenuating zone, and selectivelyangularly movable means for selectively aiming at a target emanatingelectromagnetic signals, for forming an electromagnetic wave signalemanation from a said target into a beam of discrete cross-sectionalsize substantially smaller at said mask than the effective area of saidsignal attenuating zone and substantially larger than said signalpassing zones and being of a size to overlap a plurality of said signalpassing zones over a major portion of said signal attenuating zone. 17.A bit detector according to claim 17, said signal passing lesserattenuating zones being apertures bordered by signal attenuatingmaterial which has greater signal attenuating characteristics than thesignal attenuating characteristics across said apertures. 18. A hitdetector according to claim 16, said variably spaced lesser attenuationzones varying in inter-zone spacing as a function of the distance ofsets thereof from a given point. 19. A hit detector according to claim18, said inter-zone spacing varying as an increasing function ofincreasing distance of sets of said lesser attenuating zones from apoint. 20. A hit detector according to claim 16, and a further maskfixed with respect to the first said mask and having a furtherdifferential signal attenuating pattern formed thereon and having asignal passing zone aligned in signal passing relation with a portion ofsaid signal attenuating and signal passing zones of lesser attenuationon the first said mask. 21. A selectively angularly movable photoscopearrangement comprising:

a photosensitive element, and a digital gray scale mask disposed in thepath of energy pickup by said photosensitive element, and means forforming an energy beam of discrete cross-sectional size substantiallysmaller at said mask than the effective digital gray scale portion ofsaid mask and for traversing said energy beam across said digital grayscale mask as a function of angular motion of said photoscopearrangement relative to a source of photo-energy from which a saidenergy beam may be formed,

said photosensitive element, digital gray scale mask. and last-namedenergy beam forming means being angularly movable as an aiming unit forselectively aiming thereof at a source of photo energy,

and means for restricting the lateral area from which said energy beamis formed, at any given directional position of the photoscopearrangement, to a restricted angle of view extending forwardly from saidphotosensitive element, digital gray scale mask and energy beam formingmeans.

22. A photoscope arrangement according to claim said digital gray scalemask including a knife edge photo transmission opening formed laterallyadjacent a digital gray scale pattern.

23. A photoscope according to claim 2],

said digital gray scale mask comprising a photo transmissive elementhaving spaced alternate zones thereon of differing photo transmissivity,

said zones being disposed in sets varying in set transmissivity as afunction of the set distance from a selected spatial point laterallythereof.

24. A photoscope according to claim 23,

said digital gray scale mask including a knife edge photo transmissionopening formed laterally adjacent a digital gray scale pattern formed bysaid spaced zones of one degree of photo transmissivity and otheralternate intervening zones of a different degree of phototransmissivity,

said knife edge photo transmission opening being of substantially largersize than a plurality of said spaced zones of one degree of phototransmissivity.

25. A photoscope according to claim 21,

said digital gray scale mask comprising an element having a plurality ofeffective transmission zone holes formed therein at spaced intervals,

said holes being differently spaced from one another as a function oftheir position with respect to a particular given spatial point.

26. A photoscope according to claim 25,

said digital gray scale mask further having a knife edge phototransmission opening of substantially larger size than a plurality ofsaid spaced holes and spaced to one lateral side of said holes.

27. A photoscope according to claim 26,

said particular given spatial point being disposed within said knifeedge opening.

28. A photoscope according to claim 25,

said holes forming lines of spaced holes, the holes in said lines beingdifferently spaced from the holes in other lines as a function of thelateral distance of said lines from a particular given spatial point.

29. A photoscope according to claim 28,

said digital gray scale mask further having a knife edge phototransmission opening of substantially larger size than a plurality ofsaid spaced holes and spaced to one lateral side of said holes,

said particular given spatial point being disposed laterally beyond theeffective knife edge formed by said knife edge opening.

30. A photoscope according to claim 29,

said digital gray scale mask comprising a planar sheet having said holesformed therein and extending therethrough.

31. A hit detecting arrangement comprising:

a target light signal source, means selectively angularly movablerelative to said target light signal source for forming a signal fromsaid light signal source into a correspondingly selectively angularlymovable beam of discrete crosssection, and a photoscope for detectingsignals from said target signal source when said photoscope iseffectively directed at said target signal source, said photoscopecomprising a photosensitive element and a digital gray scale maskdisposed in the path of energy pickup by said photosensitive elementfrom said beam forming means, said beam discrete cross-section at saidmask being substantially smaller than the effective digital gray scaleportion of said digital gray scale mask. 32. A hit detecting arrangementcomprising: a target light signal source, and a photoscope selectivelyangularly movable relative to said target light signal source fordetecting signals from said target signal source when said photoscope iseffectively directed at said target signal source, said photoscopecomprising a photosensitive element and a digital gray scale maskselectively disposed in the path of energy pickup from said target lightsignal source by said photosensitive element and in sequential orderalong an imaginary longitudinal line extending through said hitdetecting arrangement, and said digital gray scale mask including knifeedge photo transmission opening formed laterally adjacent a digital grayscale pattern, means disposed in spaced relation from saidphotosensitive element and selectively angularly movable with saidphotosensitive element and digital gray scale element for forming asignal from said light signal source into a beam of discretecrosssection and thereby selectively aiming said beam toward said grayscale mask and said photosensitive element, and for effective beamalignment with said photosensitive element as a function of saidselective aiming, said beam discrete cross-section at said mask beingsmaller than both said digital gray scale pattern and said knife edgephoto transmission opening. 33. A hit detecting arrangement according toclaim 32,

and a field stop mask having a generally triangular field stop apertureformed thereon. 34. A hit detecting arrangement for a target having asignal emanating therefrom, comprising:

a detector for said target signal, and an analog simulating gray scalesignal transmission attenuating unit disposed in signal pathintercepting relation to said detector, said attenuating unit having ageneral gray scale signal transmission ratio which varies as a generalfunction of transverse distance from a given zero spatial point,

said attenuation unit comprising a signal passing section havingmultiple discrete attenuation zones each of which has substantially thesame unit value of total attenuation therepast, and which discreteattenuation zones are varied in spacing therebetween to effect acorresponding varied signal response curve by a signal beam traversedacross said section,

and means selectively angularly movable relative to said target forforming said target signal into a signal beam of discrete cross-sectionsubstantially smaller at said mask than said digital gray scaletransmission unit,

which beam is movable laterally across said gray scale signaltransmission attenuating unit as a function of lateral angulardirectional positioning and movement of said arrangement relative to theeffective direction of emanation of a target signal from said target.

35. A hit detecting arrangement for a target having a signal emanatingtherefrom, comprising:

a detector for said target signal,

and an analog simulating gray scale signal transmission attenuating unitdisposed in signal path intercepting relation to said detector,

said attenuating unit having a general gray scale signal transmissionratio which varies as a general function of transverse distance from agiven zero spatial point,

and means selectively angularly movable relative to said target forforming said target signal into a signal beam of discrete cross-sectionsubstantially smaller at said mask than said digital gray scaletransmission unit,

which beam is movable laterally across said gray scale signaltransmission attenuating unit as a function of lateral angulardirectional positioning and movement of said arrangement relative to theeffective direction of emanation of a target signal from said target,

and a further field mask having a generally triangular field stopaperture zone, the apex of which is in close spatial coordinaterelationship with said zero spatial point.

36. A hit detecting arrangement according to claim said field mask beingspaced from said gray scale signal attenuating unit. 37. A hit detectingarrangement according to claim and a signal-converging field lensdisposed between said gray scale attenuating unit and said signaldetector.

t i t k UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION December 18, 1973 PATENT NO.

DATED INVENTOR(S) I Column 6, Line 43,

Column 7, Line 54,

Column 7, Line 59,

Column 7, Line 66,

Column Column 13, Line 35,

[SEAL] Michael A. Kott It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

10, Line 17,

CCCZl XP 3 9 780 g 300 v b 1 Change "wil" to ---wil1- Change "17" to---l6 Bigncd and Scaled this Twenty-sixth Day or May I98] RENE D.TEGTMEYER Arresting Oflicer Acting Commissioner of Parents andTrademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION PATENT NO. 3,780,300

DATED December 18, 1973 |NVENTOR(S) 1 Michael A. Kott It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 6, Line 43, After "G insert ----l--, so the equation will readmin 1 Column 7, Line 54, After "G insert so the equation will readColumn 7, Line 59, After "G insert so the equation will read Column 7,Line 66, Change the equation "X to read ----X 1 Column 10, Line 17,Change "wil" to ---will Column 13, Line 35, Change "17" to --l6 Signedand Scaled this .4 ttest:

RENE D. TEGTMEYER Attestiag Oflicer Acting Commissioner of Patents andTrademarks

1. For use in a hit indicating arrangement having a movable targetsource of electromagnetic wave signal emanations, a selectivelyangularly aimable hit detector for detecting the aiming of said detectorat said source within a selected zone indicating a scorable aimed hit,said hit detector being selectively angularly movable and comprising:electromagnetic wave signal detection means, and a mask for said signaldetection means, said mask forming a knife edge signal attenuating zoneadjoining a signal passing zone, said mask having a further signalattenuating zone interspersed with spaced signal-passing apertures, andselectively angularly movable means for forming said signal emanationsinto a beam of discrete cross-sectional size substantially smaller atsaid mask than either of said signal attenuating zones, the lateralposition of which beam at said mask is a function of the directionalaiming of said Hit indicator in the direction of and relative to saidtarget.
 2. A hit indicator according to claim 1, further comprisingthreshold gate means responsive to the output from said detection means,and indicating means operatively connected to the output of saidthreshold gate means, said threshold gate means enabling indicationoperation of said indicating means upon the output of said detectionmeans exceeding a selected quantum value.
 3. A hit detector according toclaim 1, said signal attenuating zones comprising signal blocking zones.4. A hit detector according to claim 1, said spaced signal-passingapertures being disposed in rows of increasing inter-aperture spacing asa function the transverse distance of a row from said knife edge.
 5. Ahit detector according to claim 1, the inter-row spacing increasing as afunction of the transverse distance of a row from said knife edge.
 6. Ahit detector according to claim 4, said apertures forming an envelopetapering outwardly in a transverse direction away from and normal tosaid knife edge.
 7. A hit detector according to claim 5, said knife edgebeing disposed in signal blocking relation at the medial section of saiddetector.
 8. A hit detector according to claim 6, said detector being ofgenerally uniform response across its effective signal detector width asdetermined by the signal passing portions of said mask.
 9. A hitdetecting arrangement for a target having signal emanations therefromcomprising: a detector responsive to said signal emanations, mask meansfor said detector, said mask means including a first signal passingsection affording a first signal response curve, and a second differentsignal passing section affording a second modifying signal responsecurve, one of said signal passing sections being formed by multiplediscrete attenuation zones each of which has substantially the same unitvalue of total signal attenuation therepast, and which discrete signalattenuation zones are varied in spacing therebetween to effect acorresponding varied signal response curve by a signal beam traversedacross said one signal passing section, the signal output curve of saiddetector being a composite of said signal response curves, and meansselectively angularly movable relative to said target, for formingsignal emanations from said target into a beam of discrete cross sectionsubstantially smaller at said mask means than either of said first orsecond signal passing sections, and the said beam being movable acrosssaid mask means.
 10. A hit detecting arrangement for a target havingsignal emanations therefrom comprising: a detector responsive to saidsignal emanations, mask means for said detector, said mask meansincluding a first signal passing section affording a first signalresponse curve, and a second different signal passing section affordinga second modifying signal response curve, the signal output curve ofsaid detector being a composite of said signal response curves, andmeans selectively angularly movable relative to said target, for formingsignal emanations from said target into a beam of discrete cross sectionsubstantially smaller at said mask means than either of said first orsecond signal passing sections, and the said beam being movable acrosssaid mask means, said first signal passing section having an effectiveknife edge signal transmission attenuation transition zone with a firstsignal transmission zone on one lateral side of said signal transmissionattenuation transition zone, and having a signal attenuation zone ofgreater signal attenuation effect than said signal transmission zone anddisposed on the opposite side of said signal transmission attenuationtransition zone, and said second signal passing section comprising aplurality of spaced discrete signal passing zones of varying spacingacross said second signal passing section as a general Function of thespatial relationship of said spaced discrete zones to said knife edgetransition zone, and affording a second signal response curve differingand generally complementing said first signal response curve togenerally simulate a desired total signal response curve.
 11. A hitdetector arrangement according to claim 10, said second signal passingsection including a signal attenuation pattern portion having a firstsignal transmission zone which has a signal attenuating characteristic,and an effectively generally knife edged signal attenuating portion ofincreased signal attenuation effect adjoining said first signaltransmission zone and having a signal attenuating characteristic ofgreater signal attenuation effect than said first signal transmissionzone.
 12. A hit detector arrangement according to claim 11, both of saidknife edged attenuation portions being commonly adjoining and havingoppositely facing effectively knife edged signal transmission transitionzones spaced from one another.
 13. A hit detecting arrangement for atarget having signal emanations therefrom comprising: a detectorresponsive to said signal emanations, mask means for said detector, saidmask means including a first signal passing section affording a firstsignal response curve, and a second different signal passing sectionaffording a second modifying signal response curve, the signal outputcurve of said detector being a composite of said signal response curves,and means selectively angularly movable relative to said target, forforming signal emanations from said target into a beam of discrete crosssection substantially smaller at said mask means than either of saidfirst or second signal passing sections, and the said beam being movableacross said mask means, said second signal passing section comprisingsubstantially the same constant size light transmission zones and beingof zonally varying light quantum transmissivity.
 14. A hit detectorarrangement according to claim 10, said zonally varying light quantumtransmissivity zones being formed by constant sized holes in said maskat varying spacing.
 15. A hit detector arrangement according to claim13, said first signal passing section including an aperture bounded by aknife edge, said knife edge being spaced from said varyingly spacedholes.
 16. A hit detector arrangement comprising: electromagnetic wavesignal detection means, and a mask for said signal detection means saidmask having a signal attenuating zone and a plurality of variably spacedapart substantially the same constant size signal passing zones oflesser attenuation than the total attenuation of said signal attenuatingzone and being within said signal attenuating zone, and selectivelyangularly movable means for selectively aiming at a target emanatingelectromagnetic signals, for forming an electromagnetic wave signalemanation from a said target into a beam of discrete cross-sectionalsize substantially smaller at said mask than the effective area of saidsignal attenuating zone and substantially larger than said signalpassing zones and being of a size to overlap a plurality of said signalpassing zones over a major portion of said signal attenuating zone. 17.A hit detector according to claim 17, said signal passing lesserattenuating zones being apertures bordered by signal attenuatingmaterial which has greater signal attenuating characteristics than thesignal attenuating characteristics across said apertures.
 18. A hitdetector according to claim 16, said variably spaced lesser attenuationzones varying in inter-zone spacing as a function of the distance ofsets thereof from a given point.
 19. A hit detector according to claim18, said inter-zone spacing varying as an increasing function ofincreasing distance of sets of said lesser attenuating zones from apoint.
 20. A hit detector according to claim 16, and a further maskfixed with respect to the first said mask and having a furtherdifferential signal attenuating pattern formed thereon and having asignal passing zone aligned in signal passing relation with a portion ofsaid signal attenuating and signal passing zones of lesser attenuationon the first said mask.
 21. A selectively angularly movable photoscopearrangement comprising: a photosensitive element, and a digital grayscale mask disposed in the path of energy pickup by said photosensitiveelement, and means for forming an energy beam of discretecross-sectional size substantially smaller at said mask than theeffective digital gray scale portion of said mask and for traversingsaid energy beam across said digital gray scale mask as a function ofangular motion of said photoscope arrangement relative to a source ofphoto-energy from which a said energy beam may be formed, saidphotosensitive element, digital gray scale mask, and last-named energybeam forming means being angularly movable as an aiming unit forselectively aiming thereof at a source of photo energy, and means forrestricting the lateral area from which said energy beam is formed, atany given directional position of the photoscope arrangement, to arestricted angle of view extending forwardly from said photosensitiveelement, digital gray scale mask and energy beam forming means.
 22. Aphotoscope arrangement according to claim 21, said digital gray scalemask including a knife edge photo transmission opening formed laterallyadjacent a digital gray scale pattern.
 23. A photoscope according toclaim 21, said digital gray scale mask comprising a photo transmissiveelement having spaced alternate zones thereon of differing phototransmissivity, said zones being disposed in sets varying in settransmissivity as a function of the set distance from a selected spatialpoint laterally thereof.
 24. A photoscope according to claim 23, saiddigital gray scale mask including a knife edge photo transmissionopening formed laterally adjacent a digital gray scale pattern formed bysaid spaced zones of one degree of photo transmissivity and otheralternate intervening zones of a different degree of phototransmissivity, said knife edge photo transmission opening being ofsubstantially larger size than a plurality of said spaced zones of onedegree of photo transmissivity.
 25. A photoscope according to claim 21,said digital gray scale mask comprising an element having a plurality ofeffective transmission zone holes formed therein at spaced intervals,said holes being differently spaced from one another as a function oftheir position with respect to a particular given spatial point.
 26. Aphotoscope according to claim 25, said digital gray scale mask furtherhaving a knife edge photo transmission opening of substantially largersize than a plurality of said spaced holes and spaced to one lateralside of said holes.
 27. A photoscope according to claim 26, saidparticular given spatial point being disposed within said knife edgeopening.
 28. A photoscope according to claim 25, said holes forminglines of spaced holes, the holes in said lines being differently spacedfrom the holes in other lines as a function of the lateral distance ofsaid lines from a particular given spatial point.
 29. A photoscopeaccording to claim 28, said digital gray scale mask further having aknife edge photo transmission opening of substantially larger size thana plurality of said spaced holes and spaced to one lateral side of saidholes, said particular given spatial point being disposed laterallybeyond the effective knife edge formed by said knife edge opening.
 30. Aphotoscope according to claim 29, said digital gray scale maskcomprising a planar sheet having said holes formed therein and extendingtherethrough.
 31. A hit detecting arrangement comprising: a target lightsignal source, means selectively angularly movAble relative to saidtarget light signal source for forming a signal from said light signalsource into a correspondingly selectively angularly movable beam ofdiscrete cross-section, and a photoscope for detecting signals from saidtarget signal source when said photoscope is effectively directed atsaid target signal source, said photoscope comprising a photosensitiveelement and a digital gray scale mask disposed in the path of energypickup by said photosensitive element from said beam forming means, saidbeam discrete cross-section at said mask being substantially smallerthan the effective digital gray scale portion of said digital gray scalemask.
 32. A hit detecting arrangement comprising: a target light signalsource, and a photoscope selectively angularly movable relative to saidtarget light signal source for detecting signals from said target signalsource when said photoscope is effectively directed at said targetsignal source, said photoscope comprising a photosensitive element and adigital gray scale mask selectively disposed in the path of energypickup from said target light signal source by said photosensitiveelement and in sequential order along an imaginary longitudinal lineextending through said hit detecting arrangement, and said digital grayscale mask including knife edge photo transmission opening formedlaterally adjacent a digital gray scale pattern, means disposed inspaced relation from said photosensitive element and selectivelyangularly movable with said photosensitive element and digital grayscale element for forming a signal from said light signal source into abeam of discrete cross-section and thereby selectively aiming said beamtoward said gray scale mask and said photosensitive element, and foreffective beam alignment with said photosensitive element as a functionof said selective aiming, said beam discrete cross-section at said maskbeing smaller than both said digital gray scale pattern and said knifeedge photo transmission opening.
 33. A hit detecting arrangementaccording to claim 32, and a field stop mask having a generallytriangular field stop aperture formed thereon.
 34. A hit detectingarrangement for a target having a signal emanating therefrom,comprising: a detector for said target signal, and an analog simulatinggray scale signal transmission attenuating unit disposed in signal pathintercepting relation to said detector, said attenuating unit having ageneral gray scale signal transmission ratio which varies as a generalfunction of transverse distance from a given zero spatial point, saidattenuation unit comprising a signal passing section having multiplediscrete attenuation zones each of which has substantially the same unitvalue of total attenuation therepast, and which discrete attenuationzones are varied in spacing therebetween to effect a correspondingvaried signal response curve by a signal beam traversed across saidsection, and means selectively angularly movable relative to said targetfor forming said target signal into a signal beam of discretecross-section substantially smaller at said mask than said digital grayscale transmission unit, which beam is movable laterally across saidgray scale signal transmission attenuating unit as a function of lateralangular directional positioning and movement of said arrangementrelative to the effective direction of emanation of a target signal fromsaid target.
 35. A hit detecting arrangement for a target having asignal emanating therefrom, comprising: a detector for said targetsignal, and an analog simulating gray scale signal transmissionattenuating unit disposed in signal path intercepting relation to saiddetector, said attenuating unit having a general gray scale signaltransmission ratio which varies as a general function of transversedistance from a given zero spatial point, and means selectivelyangularly movable relative to said target for forming said target signalinto a signal beam of discrete cross-section substantially smaller atsaid mask than said digital gray scale transmission unit, which beam ismovable laterally across said gray scale signal transmission attenuatingunit as a function of lateral angular directional positioning andmovement of said arrangement relative to the effective direction ofemanation of a target signal from said target, and a further field maskhaving a generally triangular field stop aperture zone, the apex ofwhich is in close spatial coordinate relationship with said zero spatialpoint.
 36. A hit detecting arrangement according to claim 35, said fieldmask being spaced from said gray scale signal attenuating unit.
 37. Ahit detecting arrangement according to claim 36, and an objectivesignal-gathering and converging means spaced from said field mask by adistance substantially equal to the focal length of saidsignal-gathering and converging means.
 38. A hit detecting arrangementaccording to claim 37, and a signal-converging field lens disposedbetween said gray scale attenuating unit and said signal detector.